1. Field of the Invention
The present invention relates to a gas discharge lamp base with a starting device.
2. Description of the Background Art
A gas discharge lamp base with a starting device is known from U.S. Pat. No. 5,510,967 A. In the case of the gas discharge lamp base known from U.S. Pat. No. 5,510,967 A, a tubular jacket section of the gas discharge lamp is pressed into the gas discharge lamp base by a slotted ball. Two contact bars arranged inside the gas discharge lamp base guarantee electric contact of the electric current lead-in wire and the current return wire with the respective terminals of the starting device. According to U.S. Pat. No. 5,510,967 A, the starting device has a compact design in the form of an elongated cylinder which extends inside the gas discharge lamp base perpendicular to the longitudinal extent of the gas discharge lamp. However, precise details regarding the internal structure of the starting device cannot be obtained from U.S. Pat. No. 5,510,967 A.
A similar gas discharge lamp base is known from U.S. Pat. No. 5,659,221 A, but instead of the slotted ball, a slotted truncated conical wedge is used to establish the press connection.
German Patent Application 196 10 385 A also describes a gas discharge lamp base with a starting device. According to German Patent Application 196 10 385 A, two electric terminals of the starting device, a first winding of a trigger pulse transformer and two main electrodes of the gas discharge lamp are connected in series. In addition, the two electric terminals of the starting device are connected to one another by a series connection of a capacitor across an ohmic resistor. A series connection of a second winding of the starting impulse transformer with a spark gap is connected in parallel with the capacitor. The starting impulse transformer, including the additional electronic components, the electric terminals, part of the gas discharge vessel, and part of the outer line running along the gas discharge vessel are completely or partially sheathed or cast with a plastic material to form the gas discharge lamp base.
German Patent Application 195 41 438 A describes a gas discharge lamp with a starting device where the high voltage-carrying components of the starting device are arranged in the lamp base, whereas the low voltage-carrying components are arranged in the lamp socket.
U.S. Pat. No. 5,838,109 A discloses a starting device for a discharge lamp with a starter circuit and a noise filter circuit. This starting device, however, is not arranged in a lamp base.
German Patent Application 196 10 388 A discloses another gas discharge lamp base with a starting device. The starting device according to German Patent Application 196 10 388 A has a high voltage capacitor and a Tesla transformer. The two latter components are arranged in such a way that the high voltage capacitor is surrounded by the secondary coil of the Tesla transformer.
It is therefore an object of the present invention to provide a gas discharge lamp base with a starting device having improved operational reliability in comparison with the known gas discharge lamp bases.
This object is achieved by a gas discharge lamp base with a starting device having a carrier part for electronic components of the starting device, wherein the carrier part has a first side and a second side, with only high voltage-carrying components of the starting device being arranged on the first side of the carrier part and only low voltage-carrying components of the starting device being arranged on the second side of the carrier part, and wherein at least one starting transformer being arranged on the carrier part as the high voltage-carrying component, at least the following components being arranged on the carrier part as the low voltage-carrying components: a spark gap and a starting capacitor, at least the following components are also arranged on the carrier part as the high voltage-carrying components: an interference suppression coil and a high voltage capacitor, and in addition, at least the following components are also arranged on the carrier part as the low voltage-carrying components: an interference suppression capacitor and an ohmic resistor.
The improved operational reliability of the present invention is achieved through complete spatial separation of the high voltage-carrying components from the low voltage-carrying components, with all these components nevertheless being accommodated in the gas discharge lamp base so that the gas discharge lamp base does not have to be connected to a power supply over a high voltage interface, but instead can be connected over a low voltage interface. With regard to the definition of terms, it should be pointed out that xe2x80x9clow voltagexe2x80x9d is understood herein to refer to a voltage of up to a few kV (kilo Volts). In contrast with that, the term xe2x80x9chigh voltagexe2x80x9d here refers to a voltage above approximately 10 kV, in particular a voltage of a few tens of kV.
The special three-dimensional arrangement of the interference suppression coil(s), being arranged with respect to the direction of gas discharge, contributes to an especially good electromagnetic compatibility of the gas discharge lamp base with a starting device.
Furthermore, especially good high voltage isolation and thus an especially good operational reliability is realized.
A labyrinth in conjunction with the top part of the housing and the carrier part forms a longer path for any creep current that may occur and is therefore an especially effective insulation measure which contributes toward an improvement in operational reliability in an advantageous manner. Similar advantages are realized with respect to the bottom part of the housing.
A high voltage strength of the gas discharge lamp base is improved due to the closed outer contour of the gas discharge lamp base, and the thermal load-bearing capacity of the electric components arranged in the gas discharge lamp base is reduced due to the radiant heat emitted by the gas discharge, and failure of the components contained in the gas discharge lamp base is prevented.
The planar conductor frame (also called a lead frame) offers the advantage that the terminals can be welded in one plane at the time of manufacture. The lead frame also offers other advantages: thicker circuit board conductors than in the case of printed circuits, a greater strength of the carrier due to the plastic-sheathed circuit board conductors, and the creep paths can be lengthened by integrally molded ribs.
After assembly of the components on the high voltage side of the carrier part, its walls are treated with a so-called primer which ensures a good bond between the inside wall of the high voltage space and the subsequently introduced casting compound. This primer is poured into the high voltage compartment and is poured out again immediately. Nevertheless, primer can still penetrate into the bushings for the terminal wires. To prevent this, the partition between the high voltage side and the low voltage side of the carrier part should be absolutely tight. This, however, cannot be achieved in the conventional art, because of terminal wires passing through boreholes.
The present invention also remedies this situation because the connection between the bottom of the carrier part and the metal tube and the contacting of the ends of the tubes on the circuit board conductors can be designed to be tight in a reliable manner.
Thus, the insertion of the terminal wires of the components of the high voltage side into the metal tubes is facilitated.
This facilitates the insertion of the tubes, which are fixedly connected to the bottom of the carrier part, into the holes provided in the circuit board conductors of the lead frame. In addition, by means of a protrusion of the edges of the holes in welding, a reserve of material is made available.
The joint welding of the ends of the tubes to the respective terminal wire and the circuit board conductor permits an absolutely tight seal.
In addition, the metal tubes also have the function of securing the lead frame after welding, optionally supported by lugs provided on the top part of the carrier.
Finally, the metal housing surrounding the lamp base has the advantage of good shielding with respect to the outside. It is irrelevant here how the interference suppression coils are arranged with respect to the gas discharge burning in the gas discharge vessel.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.